Project Summary Every time an incision is made, a wound is created. Over 70 million surgeries were performed in the United States in 2000 with over 50% requiring postsurgical wound care. In addition, chronic wounds affect 6.5 million patients with over $25 billion spent annually on treatment. The economic and social impact of wound healing to our society requires further research to better understand the mechanisms regulating tissue repair. In previous studies, we have shown that genetic variations in Interferon Regulatory Factor 6 (IRF6) identify individuals at risk for poor healing outcome, suggesting that IRF6 is a novel transcriptional regulator of tissue repair. We have evidence that both downregulation and upregulation of Irf6 in the mouse alter different aspects of tissue repair, suggesting that the proper homeostasis of Irf6 is required for adequate healing. Furthermore, Irf6-deficient keratinocytes are impaired in their ability to close an in vitro scratch wound. These keratinocytes are larger, more round, and exhibit more stress fibers and increased RhoA activity compared with wild-type cells. Arhgap29, a RhoA-specific activating protein, is upregulated during wound healing and is downregulated in Irf6-deficient tissues, making it a perfect downstream effector. Although it is clear that IRF6 expression is important for normal wound healing, essentially nothing is known about its cellular or molecular mechanism of action. The overall goal of this study is to take advantage of our unique murine and patient cells, in combination with unique murine models, to elucidate how IRF6 contributes to tissue repair. We hypothesize that IRF6 regulates epidermal migration by inhibiting RhoA GTPase through Arhgap29. We propose two aims to test this hypothesis: 1) Identify the mechanism of IRF6-dependent keratinocyte migration, and 2) Determine how ARHGAP29 mediates the function of IRF6. The successful completion of this project will establish the contribution of IRF6 in tissue repair and provide a basis for identifying therapeutic targets involved in wound healing.